1. Field of the Invention
This disclosure relates generally to mechanical and/or electro-mechanical power modulation devices and methods. More particularly, this disclosure relates to continuously and/or infinitely variable, planetary power modulating devices, and methods for modulating power flow in a power train or drive, such as power flow from a prime mover to one or more auxiliary or driven devices.
2. Description of the Related Art
Continuously variable transmissions (CVT) having spherical planets such as those generally described in U.S. Pat. No. 7,011,600 to Miller et al, U.S. Pat. No. 5,236,403 to Schievelbusch, or U.S. Pat. No. 2,469,653 to Kopp, typically have a rotatable support member or an idler component in contact with each spherical planet. In some systems, the idler is a generally cylindrical member located radially inward of each spherical planet. During operation of these types of CVTs, the spherical planets exert forces on the idler that generate high stress at the location contacting the spherical planets. The type of stress is commonly known as a hertzian contact stress. Fatigue life and/or durability of a rolling element, such as an idler, is a function of the hertzian stress exerted on the rolling element over time. High stress exerted on the idler component leads to lower fatigue life and lower efficiency performance of the CVT.
Thus, there exists a continuing need for devices and methods to improve the fatigue life of idler components. Embodiments of power modulating devices and/or drivetrains described below address one or more of these needs.